1. Field of the Invention
The present invention relates to a film forming method and a film forming apparatus for a substrate.
2. Description of the Related Art
In a photolithography process in the semiconductor device fabrication processes, for example, a resist coating treatment in which a resist solution is applied to the front of a wafer to form a resist film, exposure processing in which the wafer is exposed in a pattern, a developing treatment in which development is performed for the exposed wafer, and the like are performed to form a predetermined circuit pattern on the wafer.
In this event, in the resist coating treatment and the developing treatment, a film forming step is performed in which a treatment solution is supplied onto the wafer to thereby form a film of the treatment solution on the wafer. For example, in the resist coating treatment, the wafer is rotated at a predetermined speed with being suction-held by a spin chuck, and the resist solution is supplied to the center of the rotated wafer, whereby the resist solution is diffused to form the resist film on the wafer.
In order to improve yields of the wafer, it is necessary to uniformly form the resist film to a predetermined thickness. The important factors for the formation are the temperature of the resist film and the humidity of an atmosphere therearound. In other words, the thickness of the resist film is influenced by the temperature of the resist solution and the humidity of the atmosphere therearound, and thus, for example, when the temperature of the resist solution is high, the resist solution vaporizes, and the film thickness correspondingly decreases. Accordingly, the temperature distribution of the resist solution on the wafer W is kept within a predetermined range, thereby improving the uniformity in thickness of the resist film.
The resist coating unit in which the aforementioned resist coating treatment, however, is not provided with a measuring device for measuring the temperature of the wafer, and thus the temperature is not been measured. When the thickness of the resist film is corrected to be uniform, an adequate temperature distribution or the like during the coating is estimated from unevenness in line width of the circuit pattern which is finally formed on the wafer to adjust the temperature and the atmosphere in the resist coating unit. As a result, it takes a long time and a great deal of labor to obtain conditions of the temperature distribution for a uniform film thickness, and, further, accuracy is not necessarily high.
The present invention is made in the viewpoints, and its object is to provide a film forming method of measuring a temperature of a substrate such as a wafer or the like and adjusting the temperature of the substrate and a humidity of an atmosphere therearound based on the result to thereby uniform the film thickness of a treatment solution and a film forming apparatus for carrying out the method.
To attain the above-described object, according to the first aspect of the present invention, the forming method of the present invention is a film forming method of forming a film of a treatment solution on a front face of a substrate in a treatment chamber, including the steps of: supplying the treatment solution to the substrate mounted on a holding member in the treatment chamber in states of gas being supplied into the treatment chamber and of an atmosphere in the treatment chamber being exhausted; and measuring a temperature of the front face of the substrate before the supply of the treatment solution.
According to the second aspect of the present invention, the forming method of the present invention is a film forming method of forming a film of a treatment solution on a front face of a substrate in a treatment chamber, including the steps of: supplying the treatment solution to the substrate mounted on a holding member in the treatment chamber in states of gas being supplied into the treatment chamber and of an atmosphere in the treatment chamber being exhausted; and measuring a temperature of the holding member before the supply of the treatment solution.
Further, the film forming apparatus of the present invention is a film forming apparatus for supplying a treatment solution to a substrate mounted on a holding member in a treatment chamber to form a film of the treatment solution on a front face of the substrate, including: a non-contact temperature measuring device for measuring at least a temperature of the front face of the substrate or the holding member.
In accordance with a result of measuring the temperature of the front face of the substrate or the temperature of the holding member, for example, the temperature of the holding member may be changed, the supply condition of the gas to the treatment chamber may be changed, the quantity of exhaust from the treatment chamber may be changed, or the supply position of the solvent vapor of the treatment solution to the substrate may be controlled. When the holding member is rotated, the rotational speed may be changed.
The measurement of the temperature of the front face of the substrate before the supply of the treatment solution enables the check of the temperature of the front face of the substrate and the temperature distribution. Then, the measured result is compared with a previously obtained ideal temperature distribution for the formation of a film with a uniform thickness, thereby predicting the film thickness of the film which will be formed in the following processing. Further, the treatment film is formed after the temperature measurement and the film thickness of the treatment film is evaluated, thereby storing the data to find and set optimal conditions. Consequently, the temperature or the like of the treatment solution or the like can be adjusted based on the measured results and corrected to make the film thickness uniform.
It is found that the temperature of the treatment solution to be supplied onto the substrate is influenced not only by the temperature of the substrate but also by the temperature of the holding member holding the substrate. The holding member of this kind in particular is often provided with a drive mechanism such as a motor and thus it is prone to accumulate heat from the motor. Accordingly, it is useful to measure the temperature of the holding member before the supply of the treatment solution to check the temperature of the holding member for the determination whether or not a uniform film will be formed.